Many city dwellers keep small pets, e.g., cats, hamsters or rabbits. Cats, in particular, are fastidious about their personal hygiene and instinctively seek to cover up their excrement with loose soil or sand. In urban environments, to meet this need, cat owners generally provide their pets with litter boxes partially filled with specially manufactured granular or pelletized "cat litter". Most such commercially available pet litter is designed to absorb the fluid from animal wastes deposited therein, forming dry lumps of solid excrement and litter clumps held together by dried pet urine. These solid wastes must be removed frequently to keep the pet happy. Most of the litter granules in the litter box may be left in, for subsequent use by the pet, if the dried waste lumps and litter clumps are extracted therefrom for disposal. This effort saves the pet owner money but has to be done regularly and is generally a process that pet owners using conventional litter boxes do not enjoy.
Various improvements on the basic animal litter box have been patented. Examples of these include: "Self-Cleaning Litter Box", U.S. Pat. No. 4,325,325 to Larter, comprising two identical rectangular containers with a perforated and somewhat shallower tray fittable between them to separate litter granules from dried waste; "Pet Litter Separator", U.S. Pat. No. 4,325,822 to Miller, also having two identical containers that can have a flat perforated screen fitted between them to separate litter from waste; and "Self Straining Animal Litter Box", U.S. Pat. No. 3,908,597 to Taylor, having a four sided open box selectively divisible by a sliding partition, two trays with perforated bases to fit on either side of the removable partition, and open-box caps to cover either open end of the four sided open box with the perforated trays placed therein.
All of these devices require the user to pick up, hold together and tip over a collection of boxes and trays and then store bulky parts of the apparatus separately for use only during the litter separation phase, thus taking up room. The screens employed therein cannot be conveniently and controllably kept free of animal waste encrustations and may cause inconvenience to a pet by snagging the pet's claws.
A need, therefore, exists for simple and compact apparatus that permits easy and clean separation of reusable pet litter from dry pet excrement, does not require separate storage of bulky components, is easily kept free of animal waste encrustations and is easy for a pet to use.